The man accused of beating a construction worker to death with a crowbar in Deerfield Beach says he was only defending himself, according to an arrest report released Thursday.

But investigators say the killing was a “seemingly unprovoked attack.”

Jonathan Schuler, 32, of West Palm Beach, is accused of killing co-worker Arcenio Alvarez, 32, of Lake Worth. Alvarez was taken to Broward Health North and died at 9:21 a.m. Wednesday.

The attack happened at about 9 a.m. Wednesday at a construction site at 700 W. Hillsboro Boulevard.

Witnesses said the men were working on the second floor at the site when, for no apparent reason, Schuler hit Alvarez on the back of his head with the metal crowbar, according to the report.

As Alvarez collapsed to the ground, Schuler continued to hit him with the crowbar, the report said. Schuler eventually dove down a trash chute to the first floor. Co-workers held him until deputies arrived. Schuler was briefly hospitalized at Broward Health North before being booked into a Broward jail.

Alvarez worked for West Palm Beach-based N&P Demolition; Schuler was contracted for one day as a day as a laborer, according to Sheriff’s spokeswoman Gina Carter.

Schuler told detectives he was at the construction site but initially denied having anything to do with Alvarez’s injuries or death.

After detectives confronted him about statements from witnesses, Schuler said he was attacked by Alvarez and several other co-workers. When asked why the others would have attacked him, he couldn’t give a reason, according to the report.

Schuler is being held without bond on a charge of premeditated murder.